Over recent years it has been increasingly difficult to manufacture television receivers entirely at one location because of unit labor costs. In many instances the CRT will be made at one location, the chassis another and the cabinet a third.
These three components must then be brought together and assembled at one of the component locations or at a separate assembly plant. This divided manufacture is particularly useful for United States final assembly because United States unit labor costs are relatively high compared to many other parts of the world. It enables components that are labor intensive to be manufactured in a different country and shipped to an assembly location in the United States.
The divided manufacture of the chassis and associated circuitry has created unique problems. One of these results from the inability to test all the chassis circuitry at the chassis manufacturing location.
The chassis commonly includes R.F. and cable input circuitry, power supply circuitry, signal circuitry, circuitry for special features such as MTS stereo, video or CRT driving circuitry, and a jack receiving unit sometimes referred to as a "jack pack". These circuits or components are usually divided into a plurality of boards that are separately screwed into the cabinet at the final assembly location.
These separate boards are tested individually at the chassis manufacture location, but cannot be tested and trimmed there together because the individual boards and components are not dedicated to one another at the chassis assembly location.
Therefore, after the boards are shipped to the final assembly location and brought together in a single cabinet, the combination of boards are trimmed and tested. If at that point one or more of the boards is rejected, there is no capability of correcting the defective board because that capability is usually or conveniently only at the chassis manufacture location.
Thus, it would be highly desirable to dedicate all these boards and components at the chassis location so they may be trimmed and tested before shipment to the final assembly location. The final assembly location would then only have to insert the chassis, connect the video circuitry to the CRT, and testing would be largely limited to the CRT driver trimming. The present invention accomplishes these objectives.
Another problem in prior chassis assembly techniques is that the individual boards are connected with small screws to the cabinet. The use of these small screws inevitably results in extra loose screws in the cabinet even with good quality control. The extra screws are not a significant cost problem, but these loose screws can short circuitry or become wedged in locations that inhibit removal of components for repair.
It would, therefore, be desirable to eliminate the use of screws for these chassis components, and the present invention achieves this result.
A still further problem is at the chassis manufacture location where four or more separate manufacturing lines are utilized to make the chassis components including R.F. and cable input circuitry, power supply circuitry, signal circuitry, circuitry for special features such as MTS stereo, video or CRT driving circuitry, and the jack pack.
The power supply components change with the size of the picture tube. The additional feature circuitry varies with the particular receiver model. These variations make it difficult to change manufacturing lines from one model to another, and the resulting reticence to change frequently from one model to another, encourages excess inventories of certain models which down the economic line reduces corporate profits, and increases costs.
Therefore, it would be desirable to reduce the number of manufacturing lines at the chassis location and encourage and facilitate changing lines from one model to another.
The same problem is exacerbated by the different chassis sizes from one receiver to another. The physical size and configuration of the chassis components for a console are frequently dramatically different from table top units and these differences require greater changes in the manufacturing lines when switching models.
The present invention eliminates or minimizes this problem by providing a common chassis configuration for the entire array of television receivers from table top to large consoles.